Power modules (power semiconductor devices) have been widely used in various types of products, such as industrial equipment, household electrical appliances, and information terminals. Such power modules to be mounted in household electrical appliances have been particularly required to have reduced sizes and higher reliability. In such power modules, power semiconductor elements incorporated therein are adapted to treat higher voltages and larger electric currents, thereby generating heat, and, therefore, there are provided metal base plates for dissipating the heat. On the other hand, there is a need for securing an insulation distance between the base plate and the electrode terminals for passing higher voltages and larger electric currents therethrough.
Therefore, Patent Document 1 and Patent Document 2 disclose power modules having electrodes placed in an upper surface of the module, a base plate placed in a lower surface opposed thereto, and a circuit part which is sealed by a resin through transfer molding method. By employing this structure, it is possible to reduce the size of the package, in comparison with cases where electrodes are placed in its side surfaces.
Further, at the same time, power modules have been required to have package forms adaptable to SiC semiconductors, which are likely to be a mainstream in the future, due to their higher operating temperatures and excellent operating efficiencies.